$-2lm - ln + 7l + 10 = 3m - 2$ Solve for $l$.
Explanation: Combine constant terms on the right. $-2lm - ln + 7l + {10} = 3m - {2}$ $-2lm - ln + 7l = 3m - {12}$ Notice that all the terms on the left-hand side of the equation have $l$ in them. $-2{l}m - 1{l}n + 7{l} = 3m - 12$ Factor out the $l$ ${l} \cdot \left( -2m - n + 7 \right) = 3m - 12$ Isolate the $l$ $l \cdot \left( -{2m - n + 7} \right) = 3m - 12$ $l = \dfrac{ 3m - 12 }{ -{2m - n + 7} }$ We can simplify this by multiplying the top and bottom by $-1$. $l= \dfrac{-3m + 12}{2m + n - 7}$